Aircraft propeller drive



Dec. 17, 1940. .w.,B. GOODMAN AIRCRAFT PROPELLER DRIVE Filed Nov. 4, 1938 ATTORNE Patented Dec. 17, 1940 UNITED STATES PATENT oFFlcE Wright Aeronautical tion of New York Corporation, a. corpora.-

Application November 4, 1938, Serial No. 238,731

3 Claims.

This invention relates to improvements in aircraft armament. and more particularly provides a coordinated power plant for aircraft incorporating a gun.

In military aircraft it has long been the practice to mount ilxed machine guns so that they re through the propeller disc, suitable synchronizing mechanism being provided so that the bullets issuing from the gun do not hit the propeller blades. As the art has developed, a need has become apparent for the use of guns of larger caliber which necessarily become heavier and have a greater force of recoil. Coincidentally, the heavier guns or light cannon should be mounted close to the axis of symmetry of the airplane to avoid poor weight distribution and to avoid instability of the aircraft which might result from placing the guns remotely with respect to the axis of symmetry or the thrust axis of the plane. In this respect, the art suggests the use of guns mounted between the cylinder rows of a V-type engine wherein the gun barrel projects through a geared propeller shaft, wherefor no synchronizing mechanism is necessary, and whereby the recoil force of the gun is directly upon the thrust axis of the propeller. However, with the present wide use of radial cylinder engines, the above indicated solution for the problem is unsatisfactory, for the engine structure does not permit of reduction gears and gun placement in favorable positions. Accordingly, it is an object of this invention to provide means by which a gun may be mounted upon the thrust axis of a propeller which is concentric with and is driven by a radial cylinder engine. y

A further object is to provide an improved typ of extension drive for an engine of high power, which is light in weight and which is not subject to the limitations which have been common to remote drives of the art.

A further object is to provide an` improved form of cowling and cooling system for a power plant which is equipped with a remotely driven propeller and a concentric gun installation.

Still another object is to provide a remote drive system between an engine and propeller, all of the elements of the power plant being rigidly associated with one another. 1

A further object is to provide, between an engine and a driven propeller rigidly connected to` ing, a further object is to provide means for obtaining access to the gun and to provide loading and unloading mechanism therefor which is accessible from the exterior of the power plant.

Further objects will be apparent from a read- 5 ing of the annexed specification and claims, and from an examination of the drawing, in which:

Fig. 1 is a longitudinal section through a portion of the improved power plant structure, showing certain of the components thereof diagram- 10 matically; and

Figs. 2, 3 and 4 are, respectively, sections on the lines 2-2, 3-3 and 4--4 of Fig. 1.

In the drawing, I0 represents the forward portion of an aircraft body, such as a nacelle or 1lil fuselage, upon which an engine II is secured. The power plant as shown incorporates an engine of the radial cylinder air-cooled type which is shown diagrammatically, and which is mounted upon the structure I0. This engine has the 20 `conventional concentric power shaft I2 upon which is-mounted, exteriorly of the engine, a drive gear I3. To the engine casing, as at I4, is bolted a substantially cylindrical housing I5 provided with an exterior wall I6 and an interior wall I'I 25 whereby the walls define therebetween an annular space, and whereby the Wall I1 defines therewithin a cylindrical space. In said annular space are disposed a pluralityof circumferentiallyspaced shafts Iiiborne at their ends in suitable bulkheads 30 I9 and 20, the right hand end of each shaft having thereon a pinion 2| meshing withv the gear I3. At their lefth-and ends, the shafts I8 carry pinions 22 meshing with a gear 23 rigid with a hollow propeller shaft 24 on which is mounted a 35 propeller 25. The shaft 24 is borne in bearings 26 and 21 carried by the housing I5. The rear end of the housing I5 per se is open as at 28, but is covered by a detachable plate 29 to protect the gears I3, 2l. The gears 22, 23 are confined within the forward portion of the housing I5, which may be detachable. Within the cylindrical space deiined by the wall Il of the housing I5 is disposed the breach portion 30 of a gun or cannon 3|, the barrel 32 thereof projecting for- 45 wardly through the hollow propeller shaft 24. The proportions of the drive assembly will be such as to accommodate the particular type of gun or cannon which is to be used, the particular gun shown being a known type of 20 m. m. rapid 50 iire cannon. It is contemplated that machine guns of .30 or .50 inch caliber, or rapid ilre cannons of 20 to 37 m. m. caliber may readily be utilized in a device of this kind.

The housing I5 is provided with access open- 55 sufficiently large size to permit of rearward withdrawalof the gun 3i afterthehousing il has been removed from the engine and the cover plate 29 removed from the housing. Supports for the gun u are provided in the form or summons n carried by bosses Il integral with the housing i5. In referring to-Fig. 4, in connection with 1, it will be noted that the gearsgiLIiy comprise a step-up transmission wherebytheseveral shaftsV il will be rotated at several times engine speed.`

'I'he ratio of the Sears 22, 23 willbe such as to provide a step-down gear of suitable ratio so that the propeller is driven either at engine speed or at less than engine speed. Thua'the gear and layshaft organization may readily comprise a propeller reduction gear, replacing the propeller reper se. 'I'he transmission organization ishighly eilicient from power capacity and weight standpoints, for the layshafts Il being plural in number divide engine powerl and due to high spoed are subject to considerablyless torque thanif they were driven at engine speed. Thus. theaggregate group of shafts i8 may be much lighter in weight than a single transmission shaft running at engine speed., Due to the relatively large diameter of the housing i5, it inherent rigidity so that, by its rigid mountingto theen` gine and to the propeller assembly,` thewhole power plant becomes an integralland rigid unit.

The power plant incorporating th'e extension n housing I5 lends itself to veryfavorable streamlining and to. greater propeller eiciency, for, as indicated, the contour of cowlng 42 may be tapered forwardly of the engine to provide a virtuallyperfect streamline nose. 'I'he propeller 25 preferably carries a spinnen I3 forming a forward streamline continuation of the cowling 42 and having, at its forward end, a central air entrance opening 44 into which coolingfair for the engine may be entrained. The cowlng 42 actually comprises two parts, includingja forward xed portion 45 which includes an'inner air directing portion 46 cooperating. in the definition of an i annular air entrance space withthe housing I5.

The propeller carries an inner spinner 41 forming a streamlined nosefor the housing i5 and cooperating with the outer spinner 48 whichcarries out the streamline of the `cowlng 45. 'Ihe rear part 4S of the cowlng 42 comprises an 'axially slidable portion movable to aposition suchas s that shown in dotted lines to definean auxiliary cooling air entrance annulus 5|,fadapted for use at low night speeds and in climb. The cowll Il,

at its trailing edge, is. provided with adjustable flaps 5i to vary the cooling air exit opening between cowlng and body, these `flaps being coinr n fications and changeait;y

I claim as myinvention: i

in the appended claims-to cover all such modil.-In an aircraft' power plant, an engine havinga short proiecting power shaft and a gear mounted ther-coman elongated substantially cylindricall housing `comprising outer and inner withinthe inner wall a hollow space, said housing being securedto theengine with the outer wall thereof clearing andembracing said gear, a plurality of circumferentially disposed layshafts` in said chamber and carriedby the housing, each i having, a pinion engaging f said engine gear, a duction gear normally incorporated in the engine hollow shaft propeller"-iournailed at the endof said housing remote `from the engine, the shaft hollow communicating vwith, said'hollow space, and means to drivesaid propeller from saidlayshafts. t t 2. In an aircraft power plant, anengine having a short proiectlngpower shaft and a gear mounted thereon, an "elongated substantially cylindrical housingfcomprising outer and inner rality of circumferentially disposed layshafts in said chamber and carried by the housing, each having a pinionengaging said engine gear, `a hollow shaft propeller journalled at the end of -saidhousing remoteffrom the engine the shaft hollow communicating `with said hollow space,

andmeans to drive said propellerh from said layshafts, said outer and inner walls having openings to provide access tosaid hollow space between the engine and propeller, and partitionsn r between the walls around the openings to isolate and seal said chamber from the hollowspace and fromthe outside of the housing.

,t concentric walls providing between said walls "'an `elongated annular-chamber and providing l n 3. In an aircraft power plant, an eng'ne `having a projecting power shaft. a housing comprising concentric cylindrical walls secured to the `engine over said shaft, the walls defining an annular chamber therebetween and a clear hollow f' space within the inner-wall, a propeller journalled on the housing andhavinga hollow shaft the hollow of which opens to said hollow space,

a plurality of Ilayshafts circumferentially disposed in said annularchamberameans driving said layshafts fromthe engine shaft, and means driving, the propeller `from-said layshaits.

j B. GOODMAN. 

